1. Field of the Invention
The present invention relates to an apparatus and method of heat blow molding, and particularly relates to heating a preform and blow molding the heated preform into a container.
2. Description of the Prior Art
An apparatus for heat blow molding a container is described, for example, by U.S. Pat. No. 4,185,812, Japanese Patent Publication No. 53-40624 and Japanese Patent Publication No. 53-40625.
The heat blow molding apparatus described in U.S. Pat. No. 4,185,812 comprises a heating station 10 and a blow molding station 12 arranged perpendicular to the heating station 10 to form an L-shaped layout, as shown in FIG. 15 of the accompanying drawings. The heating station 10 includes four carrying paths, each of which carries one preform to be heated in its upright state. The blow molding station includes a plurality of pallets 14 each of which receives a row of four heated preforms in their upright state. These pallets 14 are circulated in a rectangular path having longer and shorter sides. The longer sides of the rectangular path extend in a direction perpendicular to the direction in which the preforms are carried in the heating station 10. A set of four preforms are blow molded into containers at the middle of one of the longer sides. When each of the pallets 14 has moved to a removal section 16, the molded containers are removed out of the system.
The heat blow molding systems described in Japanese Patent Publications No. 53-40624 and 53-40625 are designed to heat and carry a row of inverted preforms simultaneously, the heated and inverted preforms being then blow molded using blow molds into containers.
The heat blow molding apparatus described in U.S. Pat. No. 4,185,812 will form an L-shaped layout because the direction in which the preforms are carried in the heating station 10 is perpendicular to the longer sides of the rectangular path in the blow molding station 12. As a result, the blow molding station 12 will not be arranged within the width of the heating station 10 to form an irregular layout. This raises a problem in that dead spaces will be created to increase an area of installation particularly when a plurality of such systems are arranged.
In particular, when beverage containers are to be molded, it is desirable to maintain a molding room clean. The maintenance of such a wide and clean area will increase the necessary cost. It is thus desired that the area of installation be reduced as much as possible.
In such a heat blow molding system, the upright preforms are heated in the heating station 10. In such a situation, the neck portions of the preforms will be topped. In addition, the heat will upwardly move along the upright preforms. This may excessively heat the preform necks and deform them. In such a case, furthermore, the carrying members for holding the upper parts of the preforms may be subjected to adverse effects from the heat.
In addition, the upright and heated preforms are blow molded also in the blow molding station 12. Therefore, the necessary parts including stretching rods for stretching the preforms in the blow molding step must be disposed above the preforms. This increases the entire height of the apparatus and thus raises a problem in securing the space of installation and also in performing the maintenance.
In the heat blow molding systems described in Japanese Patent Publications No. 53-40624 and 53-40625, the preforms are heated and blow molded in their inverted state. After the preforms have been heated at the same time, they are sequentially moved to and blow molded by the individual blow molds. Therefore, the individual heated preforms will be different from each other in time required to heat and blow mold the preforms. This raises a problem in that the quality of product becomes irregular.